Apparatus for use in the manufacture of cement



March29, 1938. vJ. H. HOFFMANN 2,112,492

APPARATUS FOR USE IN THE MANUFACTURE OF CEMENT Filed Nov. 7. 1935 J. H. mwqmsmwuq f Ill',

Patented Mar. 29, 1938l UNITED vSTATESy PATENT 4oI-Flclaz yAPPARATUS FOR USE IN THE MANUFAC- -TURE 0F CEMENT Joseph H. Hoffmann, Bethlehem, Pa., assignor ito G. Polysius Aktiengesellschaft, Dessau, Germany, a corporation of Germany Application November 7, 1935, Serial No. 48,741

18 Claims. (Cl. 263-32) This invention relates to the production of cement and has for its principal object the provision of apparatus for use with a cement kiln or furnace to more effectively and inexpensively cool the kiln product and to improve the eiciency of the kiln.

It is common practice in the production of' thus increased by the use ofpreheated air. It is 20 also conventional practicel to employ in such coolers the counterow principle, the current of air in the cooler moving from the clinkerfdischarge end to the clinker inlet end of the cooler, whereby as the air becomes heated to higher temperatures it is progressively contacted with clinker of higher temperatureythe principle and advantages of. such a process being Well-known and frequently utilized in heat exchange devices of Widely varying nature and purposef. However,

30 the application of the counteriow principle to.

the cooling of cement clinker, while effecting most efficient cooling from the standpoint of heat exchange economy, does notl result in the production of clinker in a form in which it can 35 be most eifectively ground or pulverized. Thus it is -found that rapid and. sudden quenching of the clinker from the maximum temperature acquired thereby effects some desirable change in the clinker structure which facilitates subsequent grinding, resulting in a more uniformly ground product and'reducing the power required for the operation of. the grinding apparatus and consequently the expense. Possibly this rapid quenching results in some form of crystallization of the 45 clinker structure whereby it is renderedl more friable. Of course, this` rapid quenching cannot be eiected by employment of the counterflow principle, since the clinker delivered to the cooler.

first encounters the relatively hot air which has 50 absorbed heat from passage through the cooler, and the clinker is not contacted rwith unheated air until it reaches the discharge end lof the cooler, the cooling of the clinker being quite gradual. l v,

55 It is therefore proposed as part of the present invention to deliver clinker directly from the kiln to the cooler and to cause cool air to contact the clinker as it enters the cooler, whereby the quenching of. the clinker may be effected rapidly Go :from the maximum temperature attained by the should be fairly large.

clinker, and the foregoing advantages attained.

In the preferred form of the invention a cooler of the rotary drum type is provided, the inlet end of the drum being arranged ln close proximity to the clinker discharge end of the kiln, so that the clinker may fall from the kiln into the cooler. An airy inlet is provided adjacent the inlet end of the cooler, this air inlet being so formed as to direct cooling air into contact with the hottest clinker, the arrangement preferably being such that the air passes completely through the falling clinker to ensureintimate and complete engagement between the entire mass of. yclinker and the cool air. As the result of contact with the clinker, the air isn heated to a temperature sumciently high for efcient use in theA kiln, and is introduced therein to aid in the combustion, the employment of preheated air from the cooler for secondary combustion air in the kiln being an expedient commonly adopted.

In order that the quenching of the clinker may be quite rapidly and completely effected fromthe maximum clinker temperature, the quantity of air flotving through the air inlet aforementioned It is obvious, however,'

that the introduction of a large quantity ofair into the cooler at a point so close to the delivery end of the kiln is likely to exert a very pronounced effect on the combustion processes which vtake place in the kiln, and that if air is supplied under pressure to the inlet, as is common practice'in the delivery of. airto clinker coolers, regulation of the air ow in such manner that eflcient kiln combustion is ensured may prove quite difficult. It is therefore one of the objects of the present invention .to avoid this difficulty by supplying air to the inlet at' normal or atmospheric pressure, the normal draft through the kiln being relied on to'cause flow of air throughthe inlet. Thus the quantity of air entering the inlet is made to depend upon the reduced pressure obtaining at the clinker discharge end of the kiln therefore; to a reasonable extent, on c ombustion conditions in the kiln. In other words, if combustion is` retarded in the kiln, 'the draft through the kiln is reducedand less secondary airis supplied through the cooler inlet, whereas if combustion 'isp increased, more secondary air is drawn into the cooler and delivered to the kiln to meet the increased demand. Thus by relying solely ron the kiln draft for the -introduction of secondary air, a fairly eiective regulating action is'obtained and the use of a Kcomplicated control system is avoided, the unusually close proximity of the air inlet to the kilmensuring prompt and positive regulatory action suchias would be impossible to secure if thev air inlet were more remote from the kiln. In addition, the consumption of power required for the operation'of an aifr pump or the like is' avoided.

air through the inlet will be retarded to a greaterd or less extent by the quantity of clinker entering the kiln, and it is obvious that if only a small amount of clinker or no clinker is being delivered at any given time, the quantity of air entering the inlet may momentarily exceed that required for proper combustion in the kiln. To compensate for such fluctuation in" the delivery of clinker, it is proposed as part of the present invention to provide means acting automatically to throttle the air flow whenever the latter tends to become excessive, for instance by .the association with the air inlet of a vsimple form of loaded damper; w Q

The invention also contemplates further improvements in the cooler which will extend the life of the cooler and assist in the delivery of combustion air to the kiln. `'I'hus it is a further feature ol the invention that agitation of\the v clinker and delivery thereof toward `the discharge end of the cooler is effected by inwardly directed projections which are provided with air passages through which additional secondary air may be introduced into the cooler, the projections moving through the clinker as the cooler is rotatedv the cooler to afford sufficient time for complete cooling, and it is proposed to cause a iow of air i through passages within these bailles, the air being thereafter delivered to the usual combustible mixture supply means for the kiln and thus serving aprimary combustion air, or being supplied to other apparatus requiring preheated air, the bailles being thereby cooledand te primaryair preheated.

Further objects and features of the invention will be apparent from the following description taken in connection with the accompanying drawing, in which: y

Figure 1 is a longitudinal sectional view through a cooler constructed in accordance with the principles of the invention; o

Figure 2 is a transverse section taken substantially on the line 2-2 of Figure 1;

Figure 3 is a sectional view corresponding to Figure 2' and illustrating a slightly' modified arrangement; -z l Figures 4 and 5 are fragmentary transverse and longitudinal sectional views respectively i1- lustrating a further modification; and

Figure 6 is a transversel sectional view taken substantially on the line l-l of Figure 1.

In order to facilitate an understanding of the invention, reference is made to the preferred embodiment thereof illustrated in the accompanying drawing .and specific language is employed.'

It will nevertheless be understood that no limitation of the invention is thereby intended but that lvarious alterations and further modifications are contemplated such as would occur to one skilled in the art to which the invention relates.

Itfwill be observed that the cooler shown in'thef drawing is of the rotatable drum type. the drum, indicated at Il, being preferably supported on rollers Il or in any other convenient manner whereby rotation independently of the kiln may be readily effected if desired; alternatively, the drum may be secured to or-form part of the kiln so as to partakeof rotation with the latter. The kiln I2 selected for the purpose of illustration is of the conventional rotary type, only the clinker discharge end of the kiln being shown. The kiln and coole are disposed in close proximity, the discharge end of the kiln preferably projecting into the cooler as illustrated herein, an annular end flange I4 formed on the cooler I Il and suitf able sealing means. I5 effecting a fairly tight joint between the kiln and the cooler while allowing relative rotation thereof. That end of the cooler` remote from the kiln is provided with a closure member I8 having openings I8 therein through which the Acooled clinker may be discharged and having an opening which is centrally disposed to permit the passage therethrough of a conduit 22 through which a combustible fuel mixture may be supplied to the kiln for the burning of the cement material therein. A conventional mixing chamber 23 in which suitable fuel such as powdered coal or the like and air `under pressure are introduced and formed into an intimate mixture delivers fuel to the'conduit 22, the air under pressure being suppliedfrom ablower 24. The specific construction of this ,mixing device constitutes no part of the present invention and may be modified as desired. A

As shown in Figure 1, the clinker 25 which has been formed by the burning of the cement material in the kiln I2 is discharged from the lower end of the kilnand falls as indicated at 2l into the cooler. At a point closely adjacent to and on the kilnside of the falling clinker, the cooler I0 is provided with an inlet 26 which may comprise a plurality `of openings in the wall of the cooler. Air may be supplied to the air inlet 26 from an annular chamber 29 constituted by a recess in the annular member 30, the latter being retained against rotation by any suitable. means and being preferably in sealing engagement with the periphery of the cooler II). A* conduit 32, communicatingl directly with the atmosphere and with the chamber 29 conveys air to the chamber and thence through the inlet 26 into the cooler. As the air enters the cooler it is immediately contacted with the falling clinker and, as will be observed from Figure 1, at least a portion of theb airis caused to pass completely through the falling clinker. If desired, the apertures which com.- prlse the inlet 26 mayA be tangentially disposed so as to produce a swirling motion of the incoming air about the peripheral portion of the cooler, whereby theair may be 'causedfto sweep through the clinker before passing into the main Y portion of the cooler and' into the kiln. The intimate contact between the clinker and the air which is thus effected while the clinker has an extremely high temperature results in -rapid quenching with the attendant advantages hereinbefore indicated.

' of excessive quantities of air through the inlet,

such as might interfere with proper combustion in the kiln, a damper 3B may be associated with the conduit l2, this damper being hinged as at through the conduit 32 and the inlet 26 increases,

the damper will tend to swing inwardly against the action of thespring 31 and will thus exert a throttling action. An adjustable device 38 constituting an abutment for engagement with the damper 35 may be regulated to limit the out-- ward movement of the damper so that the amount of air ilowing through the conduit 32 and serving as secondary combustion air in the kiln will not be greater than required for maximum emciency.

be modied. to a considerable extent withoutv The construction just described may of course departing from the principles of the invention as hereinbefore outlined. Thus it will be observed by reference to Figure 3 that the member 30 may be altered so that the chamber 29 from which air is supplied to the inlet 26 extends only partially about the periphery of the cooler, the

remaining portion of the cooler periphery being' employment of a regulating damper or throttle valve such as that shown in the drawing is important since variations in the amount yof clinker discharging at any instant from the kiln may. seriously ailect the quantity of incoming air and thereby impair proper combustion in the kiln.

Returning now to Figures l and 2, it will be observed that as the clinker passes into the cooler, it is engaged by a plurality of projections i5 which serve to agitate and to slowly forward the clinker toward V,the clinker discharge end of the cooler. Preferably these projections are constructed to permit flow of air therein and vfor this purpose are provided with passages d6 extending therethrough,each passage communicating at one end with the exterior of thercooler and at the other end through an elongated aperture il with the interior of the cooler, the apertures d? beingY preferably formed in thatjfa'ce of each projection which is directed away/from the kiln, in order to maintain the air in th'ejcooler Ifor alonger .period of time.` lt'will he appreciated that the air owingl into the cooler through the passages Q5 not only serves to, augment the secondary.l combustion 'air entering through the ,4

inlet 35 but also serves to maintain the projections 55 at a lower temperature to permit absorption of heat rom the clinker as the projections pass through the clinker.- Again, the maintenance of the projections at a low temperature ensures longer life and prevents premature burn- .ing out and frequent replacements.

. Repair and replacement of the projections d5 is, however, necessary from time to'time in spite of any precautions which may be taken to maintain them at a lowl temperature. It rls consequently preferredto' form these projections separately from the cooler and to insert them through apertures B8 in the peripheral wall of the cooler, the projections being removably retained in position in any convenient mannen" 'I'he apertures 68 may be tapered inwardlyA to facilitate with-4..

drawal oi' the projections from the exterior of J from. the maximum clinke "footed, and means connect ng said inlet with a.

the kiln when necessary. Each projection is furthermore lprovided at its outer end with a bafiie portion 49 which is so constructed as to cause a current of air to ilow through the passages 46 when the cooler is rotated.

In order to facilitate further cooling oi.' the clinker, a plurality of bailies 55 are provided,

these baiiles extending inwardly from the pe ripheral wall of the cooler and being disposed j generally longitudinally of the cooler. Thus as the cooler is rotated, the baiiies will successively engage and lift=the clinker, but vwill not exert any forwarding action thereon. Each bafiie 55 is preferably removably received in a longitudinally extending slot 56 in the cooler wall and may be withdrawn from the cooler for repair or replacement from the exterior thereof. Each bale 55 isfurther provided with al1 inlet opening 58 communicating with the exterior of the kiln and with a'ipassage 60 extending longitudinally of the bae, the passage 50 and the several baiiles communicating through apertures 6| in the closure member i8 with an annular chamber 62 formed in a member 55 'which is provided with a sealing iit against the outer face of the closure member ,i8 .and which is suitably retained against rotation. A conduit 66 communicates with the annularchamber 62 and with-the blower 24. Thus air owing through the passages 60 in the bailies 55 serves to protect the baiiles and prevent premature burning thereof, to complete the cooling of the clinkeraiter the initial rapid quenching,

,i materiallyv alter the function of the cooler as hereinbefore described, since they notv only serve to agitate the 'clinker but to forward the clinker .toward the discharge end of the cooler owing to their generally helical distribution about the ccobler periphery.

In spite of the relative compactness of a cooler of the character herein described, the temperavture of the clinker may be quickly reduced to the extent desired for grinding, the emciency of the' kiln may be increased by the use of the heat absorbed from ,the clinker for preheating both the primary and secondary combustion air, and the clinker is discharged from the cooler in the best condition for grinding by reason of the-'rapid and effective quenching thereof fromv the maxiters Patent is:

1. lThe combination with a rotary kiln for.

burning cement material, of a cooler lreceiving cement clinker from said kiln and discharging preheated air into isald kiln to. aid combustion" therein, said cooler having an air inlet arranged to direct cooling air through the clinker at the,

point of introduction of the clinker intogthe cooler, whereby rapid quenching of'the clinker temperature is efsource of air at substantially constant pressure, whereby the Quantity of air passing through said inletmay vary in response to variation in pressure in the material discharge end of said kiln.

2. The combination with a rotary kiln -Ior burning cement material, of a cooler receiving .cement clinker i'rom said kiln and discharging preheated air into said kiln to aid combustion therein, said cooler having an air inlet arranged to direct cooling air through the clinker at the point of introduction of the clinker into the cooler, whereby rapid quenching of the clinker 'from the maximum clinker temperature is efiected, said inlet communicating with a source oi' air at substantially constant pressure, wherebyl preheated air into said kiln to aid'combustion therein, said cooler having an air inlet arranged to direct cooling alr'through the clinker at the point of introduction of the clinker, into the cooler, whereby rapid quenching oi' the clinker 'from the maximum clinker temperature is ef- -by the quantity of air passing through said inlet may vary in response to variation in pressure in f the material discharge end of said kiln, and

means associated with said inlet for eecting progressively increased throttling of air passing therethrough as the now of air increases.

4. The combination with a rotary kiln for burning cement material to form cement clinker, of a. rotary coolersupported adjacent said kiln in communication with the material discharge end of said kiln, whereby clinker discharged from said kiln may fall into said cooler and air preheated in said cooler may pass into said kiln to assist in supporting combustion inthe latter, and an air inlet in said cooler positioned and directed l to pass' air completely through the falling clinker,

. in communication whereby rapid quenching of the clinker from the maximum clinker temperature is eiected.

5. 'I'he combination with a rotary kiln for burning cement material to form cement clinker, of a rotary cooler supported adjacent said kiln in communication with the material discharge end of said kiln, whereby clinker discharged from said kiln may fall into said cooler and air preheated ih said cooler may pass into said kiln to assist in supporting combustion in the latter, and an air inlet in said cooler positioned and directed to pass air completely through the falling clinker, whereby rapid quenching of the clinker from the maximum clinker temperature is'eiected, said airinlet communicating directly with the atmosphere, whereby air is drawn through said inlet solely as the result of kiln draft.

6. -The combination with a rotary kiln for burning cement material to forni cement clinker, of a' rotary cooler supported adjacent saidkiln with the material discharge end of; said kiln, whereby clinker discharged from 'fsaid kiln lmay fall into said cooler and air pre- .r, heated in said cooler may pass into said kiln to Vassist in supporting combustion in the latter, an

ali-inlet in said cooler positioned and directed to air' completely through the falling clinker,

whereby quenching or the clinker from the maximuin clinker temperature is eiected, said air inlet communicating directly with the atmosl heated in said cooler may pass into said kilnto assist in supporting combustion in the latter, an air inlet in said cooler positioned and directed to'pass air completely through the falling clinker, whereby rapid quenching of the clinker from the maximum clinker temperature is eiected, said air inlet communicating directly with the atmosphere, whereby air is drawn through said inlet solely as the result of kiln draft. and means automatically operable to regulate air now through said inlet to` prevent excessive iiow when the quantity "of falling clinker is decreased, said last named.l means comprising a flow controlled throttle valve associated with said inlet.

8. 'Ihe combination with 'a kiln for .burning cement material to form cement clinker, of a cooler supported vadjacent said kiln in communication with the material discharge end of said kiln, whereby clinker discharged from said kiln may fall into said cooler and air preheated in said cooler may pass into said kiln to assist in supporting combustion in the latter, and an air inlet in said cooler positioned and directed to pass air completely through the falling clinker, whereby rapid quenching of the clinker from`the'maximum clinker temperature is effected.

9. The combination with a rotary kiln for burning cement material to form cement clinker,

of a rotary cooler supported adjacent said kiln in communication with the material discharge end of said kiln, whereby clinker discharged from said kiln may fall into said cooler and air preheated in said cooler may pass into said kiln to assist in supporting combustion in the latter, and an air inlet in said cooler positioned and directed to pass air completely through the falling clinker, whereby rapid quenching of the clinker from the 'maximum clinker temperature is effected, said cooler being provided with inwardly directed pro-l said kiln may fall into said Vcooler and air preheated in 'said cooler may pass into said kiln to assist in supporting combustion in the latter, an air inlet in said cooler positioned and directed to pass air completely throughthe falling clinker, whereby rapid quenching of the clinker from-the maximum clinker temperature is reil'ected, means for supplying a. combustible mixture to said kiln,

said cooler being provided with inwardly directed projections for agitating` the clinker therein, 75

y both groups to cool said projections to Aair-ex-A .preventl premature destruction thereof and whereby the supply of combustion supporting air vpassing through said inlet may be augmented,

and additional inwardly extending projections having passages therethrough, each of said last named passages communicating at one end with the atmosphere.y

"11. A clinker cooler for use-with cement kiln,.

said cooler comprising a rotary drum having an inlet for hot clinker at one end and a discharge outlet for cooled clinker at the other end thereof, said drum having a plurality of .inwardly directedH projections near the inlet end-thereof for agitating and forwarding-the clinker toward the discharge end, and having a plurality of inwardly directed projections near the outlet end thereof for further cooling the clinker. and.means for effecting ow of air through the projections of tent s ufll 'lent to prevent overheating and premature destruction thereof. l Y l 12. 'A clinker cooler for use with a cement kiln,

said cooler comprising a rotary drum having an inlet for. hot clinker at one end and a discharge `outlet for cooled clinker at the other end thereof, said drum having a plurality`vv of inwardly directed projections near theinlet end thereof for agitating and forwarding the-elinker toward the discharge end, and having a plurality of inwardly directed projections near the outlet endthereofmeans for effecting flow of air through the projections ofV both groups to cool said projections to an extent suillcient to prevent overheating and premature destruction thereof, and means whereby air flowing through said iirst projectionsmay be caused to pass into said cooler and thence into said kiln for utilization as preheated secondary combustion air.

13.` A clinkercooler for use with a cement kiln,

said cooler comprising a rotary drum having an inlet for hot clinker at one end and a discharge outlet for cooled clinker at the other end thereof, 'said drumha'ving a plurality of inwardly directed projections near the inlet end thereof for agitating and forwarding the clinker toward the discharge end, and having. a plurality of inwardly directed projections near the outlet end thereof, means for effecting flow of' air through the projections o fboth groups to cool said projections -to an extent sulcient to prevent overheating and premature destruction thereof, means whereby air iiowing through said first projections may be caused to pass into said cooler ,and thence into Asaid kiln for utilization as preheated secondary combustion air, and means whereby air flowing through said second projections may be isolated from the interior of said cooler and delivered to the combustible mixture v"supply means for said p 'burner for use as primary combustion air.

y14. In' apparatus for use with a cement kiln having means for supplying thereto a combustible mixture, the combination with a rotary drum cooler arranged to receive lhot clinker from -said` kiln and to deliver preheated' air -to said kiln for use as secondary combustion air, of inwardly' directed projections in said cooler, said projections extending generally longitudinally of said cooler, each of said projections having a longitudinally said cooler at a point closely adjacent the clinker inlet end of the cooler for effecting rapid quench'- ing ofthe clinker from a maximum temperature and for supplying highly heated air to said kiln for secondary combustion therein.

15. A clinker cooler for use with a cement kiln,i

said cooler comprising a rotary drum having an inlet for hot clinker at one end and a discharge outlet for 'cooled clinker at the other end thereof, said drum having a pluralityV of inwardly directed projections for agitating and forwarding vthe clinker toward the discharge end, said projections being formed separately from said drum and constructed for introduction into the interior-of the drum through apertures in the drum wail from the exterior of the drum, `whereby said projections may be readily removed from said drum for repair or replacement, said projections having apertures therethrough through which air may flow to the interior of the drum-to reduce the temperature acquired by the'projections and to cool the clinker.

16. A clinker cooler for'use with a cementkiln, said cooler compri'ng a rotary drum having an inlet for hot clinker at one end and a discharge outlet for cooled clinker at the other end thereof, said drum having aplurality of inwardly directed projections for agitating and forwarding lthe clinker toward the discharge end, said projections being formed separately 'from said drum and constructed for introduction into the interior of the drum through apertures in the drum wall'from the exterior of the drum, whereby said projections may be readily removed from said drum for repair or replacement, said projections having apertures therethrough through which air may flow `to the interior of the drum to reduce lthe temperature acquired by the projections and to cool the clinker, and means associated with each projection for inducing a ilow of air through the projection when said drum is rotated.

flow of air through the clinker in accordance with pressure variation at the discharge end of the kiln. l

18. AV method offcooling cement clinker produced in a rotary kiln or the like,which includes the steps of delivering the clinker from the kiln directly into a quenching zone, causing a 'current of cool air to pass-completely through the clinker in said quenching zone and while the clinker retains its maximum temperature to rapidly quench 'the clinker, thereafter passing the clinker through an extended cooling zone and causing a current of gas to contact the clinker in said cooling zone to gradually complete the cooling of the clinker. g JOSEPHH. HOFFMANN. v

cement material therein, and varying the rate of 

